Remove offer_nice_chunk(), PL_nice_chunk and PL_nice_chunk_size.

These provided a non-public API for the hash and array code to donate free
memory direct to the SV head allocation routines, instead of returning it
to the malloc system with free().

I assume that on some older mallocs this could offer significant benefits.
However, my benchmarking on a modern malloc couldn't detect any significant
effect (positive or negative) on removing the code. Its (continued) presence,
however, has downsides

a: slightly more code complexity
b: slightly larger interpreter structure
c: in the steady state, if net creation of SVs is zero, 1 chunk of allocated
   but unused memory will exist (per thread)

So I think it best to remove it.

1 files changed, 2 insertions, 14 deletions

diff --git a/hv.c b/hv.c
index 9d7606a46c..9aa1466206 100644
--- a/hv.c
+++ b/hv.c
@@ -1105,13 +1105,7 @@ S_hsplit(pTHX_ HV *hv)
     if (SvOOK(hv)) {
 	Copy(HvAUX(hv), &a[newsize * sizeof(HE*)], 1, struct xpvhv_aux);
     }
-    if (oldsize >= 64) {
-	offer_nice_chunk(HvARRAY(hv),
-			 PERL_HV_ARRAY_ALLOC_BYTES(oldsize)
-			 + (SvOOK(hv) ? sizeof(struct xpvhv_aux) : 0));
-    }
-    else
-	Safefree(HvARRAY(hv));
+    Safefree(HvARRAY(hv));
 #endif
 
     PL_nomemok = FALSE;
@@ -1270,13 +1264,7 @@ Perl_hv_ksplit(pTHX_ HV *hv, IV newmax)
 	if (SvOOK(hv)) {
 	    Copy(HvAUX(hv), &a[newsize * sizeof(HE*)], 1, struct xpvhv_aux);
 	}
-	if (oldsize >= 64) {
-	    offer_nice_chunk(HvARRAY(hv),
-			     PERL_HV_ARRAY_ALLOC_BYTES(oldsize)
-			     + (SvOOK(hv) ? sizeof(struct xpvhv_aux) : 0));
-	}
-	else
-	    Safefree(HvARRAY(hv));
+	Safefree(HvARRAY(hv));
 #endif
 	PL_nomemok = FALSE;
 	Zero(&a[oldsize * sizeof(HE*)], (newsize-oldsize) * sizeof(HE*), char); /* zero 2nd half*/